Getting startedYeon Sik Jung puts chemicals onto a silicon wafer at start of an experiment in the clean room. Credit: D. Fox

Watching Yeon Sik Jung’s slow, careful movements, you sense that he’s doing something important. But it’s way too small to see.

Jung (pronounced Yoong) is dressed in white from head to toe. He wears a white jumpsuit, white boots, a white mask with goggles and a white cap on his head.

With a white-gloved hand, Jung lifts an eyedropper and squeezes liquid onto a flat, shiny disk. That glistening drop hides an invisible world. And Jung controls that world. Within, he is creating some of the smallest electric circuits ever made.

Jung works at Lawrence Berkeley National Laboratory’s Molecular Foundry, just outside Berkeley, Calif. A foundry is a place where tools and other parts are made out of metal. Molecules are tiny building blocks in everything from snot to snails to you and me. Put the two words together, and you have a place where scientists use molecules like Legos to build things too small to see.

Jung is currently working on an invention that could help us overcome the challenges of global warming. Another scientist, named Xiaogan Liang (pronounced Lie-Ang), stands nearby. The two scientists are trying to build tiny electrical circuits called solar photovoltaic cells within the drop of liquid. Solar cells can turn sunlight into electricity.

Filthy people

Jung, Liang and I have to wear these white suits, called “bunny suits,” because we’re in a special room called the clean room.

You may not realize it, but people are filthy—even after a bath. Your body constantly sheds flakes of dead skin. Your clothes, hair and shoes let specks of dust loose into the air. Every breath that you inhale contains more than 20,000 pieces of this invisible garbage, twirling around like loose leaves on a windy autumn day. That tiny trash doesn’t usually hurt your lungs, but it would ruin the work that Liang and Jung are trying to do.

Compared with the tiny things that Liang and Jung are building, a single flake of dandruff is huge. “A speck of dust would be like a comet,” says Liang, referring to the huge chunks of ice that fly through space. A comet hitting Earth could destroy a city, and a piece of dust landing in Jung’s little drop of liquid would ruin his miniature world, too.

So we have to cover our filthy selves in these suits. Pumps filter the air to remove any stray bits of dust. No eating or drinking is allowed. We’re not even supposed to fart. “In principle, it is not desirable to do that,” says Liang in a careful, scientific tone. “But we don’t have detectors in here.”

Every rooftop

As Liang talks, Jung lets the drop of liquid spread out on the shiny, mirror-like disk, called a wafer. Then he sets it in an oven heated to 200º Celsius. “That’s it,” says Jung through his mask. “We just need to wait a couple of hours.”

Today’s experiment is so simple that it’s almost boring to watch. But if Jung, Liang and other scientists succeed, their work could ultimately allow people to put solar photovoltaic cells on every rooftop in thousands of cities around the world, which would help reduce the amount of coal, oil and natural gas burned. That, in turn, would reduce the amount of Earth-warming carbon dioxide pumped into the air.

For a long time, photovoltaic cells have been made from a mineral called silicon. To make pure silicon, scientists actually have to melt sand or rock. It means heating the rock to more than 1,000º C—pretty much what a volcano does. And then scientists have to heat the purified silicon again, to 600º C, so it will form pure crystals. “That takes a lot of energy, and energy costs money,” says Larry Kazmerski, an electrical engineer at the National Renewable Energy Laboratory in Golden, Colo. After that, expensive robotic machines have to build patterns onto the silicon. “The processing is very involved and complex.”

So even though photovoltaic cells could help people burn less coal, oil and natural gas, they cost so much that few can afford to buy them. Even today, 40 years after the first photovoltaic cells were invented, few roofs have them.

Nanoscience, the science of very small things, could solve that problem. The term “nano” means one billionth. The term “nanometer” means one billionth of a meter—or about one billionth the length of a baseball bat.

Greasy frying pan

FocusXiaogan Liang works with the “focused ion beam” instrument in the clean room. Credit: D. Fox

Liang, Jung and other nanoscientists are coming up with a new way to build really small things without the need for such high heat and without the help of the expensive robots. The process is called “directed self-assembly,” and it’s surprisingly simple.

You mix a couple of chemicals together, put a drop of the liquid onto a piece of silicon or plastic (it doesn’t really matter what), and then those chemicals do the work for you. As the chemicals dry, the individual molecules arrange themselves into a complicated pattern, like the pattern that your grandmother might stitch on a quilt. For the photovoltaic cells, Liang and Jung want to create row after row of evenly spaced pencils that will stand up like spines on a porcupine.

If you’ve ever watched a frying pan full of grease cool off, then you’ve seen a very simple kind of self-assembly. As the pan cools, the grease forms little round droplets that sit on top the water in the pan. It happens automatically because of the way that grease and water molecules interact with each other.

Another kind of self-assembly happens when snow falls during winter. All by themselves, water molecules latch together to form beautiful, complicated six-pointed stars of ice — snowflakes. Snowflakes are so complicated that you could never cut a real one out of construction paper using scissors. And yet the mindless little molecules do it themselves.

So what if you could learn to make the molecules do what you want them to? What if you could mix two chemicals so the molecules arranged into specific shapes? What if you could control those patterns just by choosing one chemical or another? Depending on the chemicals you mixed, you might get a polka-dot pattern. Or perfectly straight pinstripes. Or spirals. Or a crisscrossed honeycomb, like in a beehive.

Liang, Jung and their boss at the Molecule Foundry (a scientist named Deirdre Olynick) are learning the art of self-assembly. They can create all of those patterns by choosing the chemicals to mix together. Today in the lab, Liang and Jung are making tiny pegs like pencils standing straight up. If it works correctly, each pencil will be exactly the same size, about one ten thousandth as wide as the sharp point of a safety pin.

Interlocking fingers

Solar cells are made of two types of material, one stacked on top of the other. When sunlight hits the cells, it knocks electrons from one layer into the other—creating electricity. (Electricity is the movement of these tiny charged electrons.) Those two layers could sit flat on top of each other, like layers in a birthday cake. But the solar cell works better if the two layers interlock. With an interlocking pattern, the two layers touch each other over more area. It gives the cells a better net for catching sunlight, and they can convert more of the sunlight into electricity. Those tiny pencils that Liang and Jung are making will be the first step in creating layers that interlock like fingers.

Close-up viewXiaogan Liang looks at the self-assembled projects under the electron microscope in the clean room. Credit: D. Fox

Self-assembly avoids the high temperatures used in making pure silicon. Never mind volcano temperatures reaching 1,000º C. Jung and Liang are cooking their drop of liquid at just 200º C—about as hot as pizza is cooked. And because the molecules arrange themselves, Jung and Liang also should not need as many expensive robotic machines to make the complicated patterns that will interlock the two layers in their solar cells.

The big challenges in self-assembly are being clean and using the right recipe. And the recipe that Jung and Liang are using today is simpler than making pizza.

“That’s the point,” says Stefano Cabrini, the director of the Molecular Foundry. “The point of self-assembly is to make something easily that you can produce many, many of.”

Invisible forest

After waiting two hours for the chemicals to bake and dry, Liang and I slip back into our bunny suits and return to the clean room.

As Liang lifts the wafer with a pair of tweezers, it’s hard to see any difference. The wafer looks shiny, just like before. The coating of chemicals on the wafer is very thin—only one ten-thousandth as thick as a sheet of aluminum foil.

In order to see the pattern that those molecular Lego blocks have formed, we need to look at it through a special microscope, called an electron microscope. This microscope is the size of a small refrigerator, with wires coming out on all sides. The picture from the electron microscope shows on a computer screen.

As Liang turns knobs to focus the microscope, a hidden world takes shape.

On the screen we see what looks like a forest of gray pencils standing straight up. If we were looking at red blood cells or little amoebas swimming in pond water, we might need to magnify the picture only 200 times. But in order to see this hidden forest of pencils, Liang has magnified the picture 590,630 times.

Each one of those pencils is only 60 atoms across. Even the most advanced silicon-carving robots today cannot carve shapes this small. But here, the researchers have done it just by mixing a couple of chemicals together. Shake and bake.

Printing money

This pencil-studded wafer that Liang and Jung have made could someday be used to print solar cells onto sheets of plastic, the same way that dollar bills are printed onto paper.

In the factory, a sheet of plastic might roll off of a giant spool. As the sheet of plastic moves, like a conveyor belt, a huge printing press would squish down on it. That printing press would have the same tiny pencil-studded pattern that Liang and Jung made today. It would press that shape into the plastic—“like kids making handprints in the mud,” says Liang. Then another chemical could be painted over the top of the plastic sheet, filling the holes made by the tiny pencils in the printing press and creating a second layer. And abracadabra—you would have a sheet of photovoltaic cells. That sheet would be rolled like toilet paper onto another huge spool.

When people build a house, they could go to the store and buy a few rolls of that solar cell paper. They’d unroll the cells onto the roof of their houses. Unlike toilet papering a house, though, this would be good for the environment. Those solar cells would convert sunlight into the electricity needed to turn on lights and run computers.

If this self-assembly works, it could allow many more people around the world to put solar cells on their buildings. “There is risk. There’s no guarantee it will work,” says Kazmerski. “But the benefit is quite incredible. It could revolutionize [solar power] very quickly if it’s successful.”

Lots of other nanoscientists around the world are working on different kinds of self-assembly. If they succeed, then self-assembly could eventually be used for making many other things, like the tiny electrical chips that run computers and iPods and radios. Self-assembly might allow scientists to make all of these things smaller than ever before. Years from now, an iPod might be the size of a dime.

These are the hopes of nanoscience, at least. Finding out whether they happen will take years of hard work. Scientists like Liang and Jung can look forward to spending a lot more time in their bunny suits.

POWER WORDS

Atom – The basic structure of a chemical element. Atoms have a nucleus that contains protons and neutrons and is surrounded by electrons that move around it in orbits at high speed. When atoms combine together they form molecules.

Bunny suit – A white suit that is worn in a clean room to prevent dirt and flakes of skin from interfering with experiments.

Chemical compound – A substance made of atoms of two or more chemical elements that are combined in molecules.

Chip – A complex electric circuit that is etched onto a tiny slice of material called a semiconductor. Chips are used in computers and most electronic devices and may contain tiny switches, capacitors and other devices.

Circuit – A closed path through which an electrical current flows. Circuits have a source of electricity, such as a battery or generator, and a wire that connects the source to a part that uses the electricity, such as a lamp or television.

Clean room – A room used in laboratory work that is kept virtually free of contaminants such as dust and bacteria.

Comet – A mass of ice, frozen gases, and dust particles that travels around the Sun in a long path.

Electricity – A form of energy produced by particles that have charge, especially electrons. Electricity can flow in an electric current, or it can be static.

Foundry – The building and works for casting metals.

Magnification – A number that shows how many times larger an object looks than it really is.

Microscope – An instrument that makes very small objects appear larger.

Electron microscope – A very powerful microscope that uses a beam of electrons, instead of light, to magnify objects that are too small to be seen with an ordinary microscope.

Molecule – A group of two or more atoms that are joined together by sharing electrons in a chemical bond.

Nanometer – One billionth of a meter.

Nanoscience – The study of things at the ultrasmall scale, usually a hundred nanometers or less.

Photovoltaic cell – A device that changes sunlight into electricity. Solar cells are used to supply power to satellites, calculators and other devices.

Printing press – A machine that uses contact to transfer letters or images onto paper.

Red blood cell – A cell that is shaped like a disk and is found in the blood of humans and other vertebrates.

Self-assembly – A process by which disorganized, disordered components create on their own some organized structure or pattern.

Silicon – A chemical element that makes up about one-fourth of the Earth’s crust.

Solar energy – Energy that comes from the sun’s radiation. Solar energy can heat up rooms that have windows facing the sun and can also be used to make electricity in solar cells.

That’s because scientists have now found a way to turn sugar into electricity. If they can find a way to make the technology work on a large scale, you may some day share your sweet drinks with your handheld video game player or cell phone.

A new technological advance could lead to cell phones that are powered by sweet drinks.

iStockphoto

The new strategy involves fuel cells, which are devices that use chemical reactions to produce electrical currents. Manufacturers already make fuel cells that depend on precious metals, such as platinum, to spark those chemical reactions. Precious metals, however, are expensive and hard to get.

For the new study, researchers from St. Louis University used a type of protein called enzymes in place of the metals. In the cells of living things, including people, enzymes are what spark chemical reactions. To keep up the pace that our bodies demand, our cells constantly produce new enzymes as the old ones break down.

Scientists had tried using enzymes in fuel cells before, but they had trouble keeping the electricity flowing. That’s because, unlike the enzymes in our cells, the enzymes in fuel cells break down faster than they can be replaced.

To get around this problem, the St. Louis researchers invented molecules that wrap around an enzyme and protect it. Inside this molecular pocket, an enzyme can last for months instead of days.

In the new fuel cells, electricity-conducting materials are attached to wires. The scientists coat each conductor with a layer of wrapped enzymes. Then, they allow a sugary liquid to ooze inside the enzyme pockets.

When the enzymes interact with the sugar molecules in the liquid, chemical reactions release a flow of electrons into the wire. This process produces both water and an electrical current that could power electronic devices.

So far, the new fuel cells don’t produce much power, but the fact that they work at all is exciting, says Paul Kenis, a chemical engineer at the University of Illinois at Urbana-Champaign.

“Just getting it to work,” Kenis says, “is a major accomplishment.”

Sugar-eating fuel cells could be an efficient way to make electricity. Sugar is easy to find. And the new fuel cells that run on it are biodegradable, so the technology wouldn’t hurt the environment.

The scientists are now trying to use different enzymes that will get more power from sugar molecules. They predict that popular products may be using the new technology in as little as 3 years.—E. Sohn

Going Deeper:

Castelvecchi, Davide. 2007. Is your phone out of juice? Biological fuel cell turns drinks into power. Science News 171(March 31):197. Available at http://sciencenews.org/articles/20070331/fob6.asp .

Sohn, Emily. 2005. Electric backpack. Science News for Kids (Oct. 5). Available at http://sciencenewsforkids.org/articles/20051005/Note3.asp .

Researchers have now found that microbes living under the ocean floor appear to produce propane and another gas called ethane. These microbes chew up ancient organic material, such as leaves and twigs buried in the sand, and they generate the gases as waste products.

That’s a surprise. Scientists had thought that propane and ethane could be produced only in the same way that petroleum is—by great heat applied to ancient, buried material.

Kai-Uwe Hinrichs examines a sample taken from a cylinder of sediment drilled out of the ocean floor.

Ocean Drilling Program Leg 201 Science Party

A team led by Kai-Uwe Hinrichs of the University of Bremen in Germany went on a research ship equipped with an enormous drill that dug out cylinders of sand or rock thousands of feet long. When the researchers examined these cylinders, they found traces of ethane and propane locked in the sediment.

Normally, to generate these gases, Earth’s heat cooks organic material in sand for many thousands of years. This can happen only at spots above cracks in Earth’s crust, where heat can leak out from inside Earth, and where thick layers of sediment would act like a blanket.

But the samples that Hinrichs and his coworkers had looked at contained thin layers of sediment. Some cylinders had also been obtained from places far from any cracks in Earth’s crust. So where could the gases be coming from?

Scientists already knew that microbes could break down organic material to produce a related, simpler gas called methane. So, undersea microbes were the only thing that made sense.

“When you can’t come up with any geologic source, then biology is an obvious candidate,” Hinrichs says.

The finding may someday lead to practical applications. Propane is valuable as a fuel, and ethane is used to make plastics. Pulling propane and ethane out of sediment is too difficult to be practical. But if scientists can better understand how microbes create the gases, they might be able to use the microbes’ methods to make ethane and propane directly from organic material.—J. Rehmeyer

Going Deeper:

Rehmeyer, Julie. 2006. Gassy bugs: Microbes may produce propane under the sea. Science News 170(Sept. 30):213. Available at http://www.sciencenews.org/articles/20060930/fob4.asp .

You can learn more about propane at en.wikipedia.org/wiki/Propane and ethane at en.wikipedia.org/wiki/Ethane (Wikipedia).

Cutraro, Jennifer. 2006. Microbes at the gas pump. Science News for Kids (April 12). Available at http://www.sciencenewsforkids.org/articles/20060412/Feature1.asp .

Sohn, Emily. 2006. Plant gas. Science News for Kids (Jan. 18). Available at http://www.sciencenewsforkids.org/articles/20060118/Note2.asp .

______. 2004. Drilling deep for fuel. Science News for Kids (Sept. 29). Available at http://www.sciencenewsforkids.org/articles/20040929/Note3.asp .

ScienceFairZone
Harvesting Biogas from Manure
www.sciencenewsforkids.org/articles/
20050504/ScienceFairZone.asp

Many vehicles run on fuels made of a blend of gasoline and ethanol. Experts at the U.S. Department of Energy say that using more ethanol would help reduce our dependence on fossil fuels.

Cars such as this one can run on a fuel called E85, which is 85 percent ethanol and 15 percent gasoline.

National Renewable Energy Laboratory

To produce enough ethanol to meet our energy needs, researchers are developing methods to turn plant parts into ethanol. They’re members of a growing movement to use renewable resources, such as plants, to provide energy.

“There’s leftover plant material everywhere,” says Jared Leadbetter. “There are rice hulls, sawdust, wood chips—plant material that’s full of energy.” Leadbetter is a microbiologist at the California Institute of Technology in Pasadena.

To tap this energy supply, scientists and engineers are turning to microbes to convert huge amounts of waste plant material into ethanol for cars.

Breaking down sugars

When tiny organisms such as yeast break down sugars to obtain energy, they produce ethanol. This process is called fermentation.

Scientists and engineers have been using fermentation for years to make ethanol from kernels of corn. But there’s a lot more to a corn plant than just the kernel. Corn plants include stalks, leaves, and the cob that’s left behind after the kernels are removed.

Microbes could help turn cornstalks and other waste plant material into a biofuel.

National Renewable Energy Laboratory

The trouble is that stalks, leaves, and other plant parts contain a complex molecule called cellulose. It’s a tough molecule to break down. In fact, our bodies can’t even digest it.

But breaking down cellulose into sugar molecules is a key step in making ethanol from the nearly 430 million tons of plant waste produced on farmland every year.

Fortunately, some organisms make compounds called enzymes that can digest, or break down, cellulose. Scientists hope to use such enzymes to produce ethanol.

Termite stomachs

Scientists are looking for these cellulose-busting enzymes in unusual places—termite stomachs, for example.

Most people think of termites as pests because of the damage that they do to homes and other structures. But termites harbor more than 100 species of bacteria in their guts—bacteria that may help us make ethanol from plant waste.

The stomachs of termites contain bacteria that can break down cellulose.

Agricultural Research Service, U.S. Department of Agriculture

These microbes digest cellulose and other complex molecules in wood. Without their bacteria, termites wouldn’t be able to survive on their woody diet.

Leadbetter and his coworkers at the U.S. Department of Energy’s Joint Genome Institute are studying the genes of microbes that produce wood-digesting enzymes. Made up of molecules called DNA, genes determine such traits as the shape of a plant leaf, the color of an animal’s coat, or the texture of a person’s hair.

“We are making a toolbox of wood-degrading enzymes and we want to tap it to obtain enzymes for making ethanol,” Leadbetter says.

Once they find the genes that control the enzymes that digest wood and those that produce ethanol, Leadbetter and his team hope to genetically modify bacteria to do both steps.

Cow stomachs

The dark depths of a cow’s stomach are home to cellulose-munching microbes as well, says Paul Weimer. He’s a research scientist with the U.S. Department of Agriculture Dairy Forage Center in Madison, Wis.

A cow’s stomach is home to cellulose-munching microbes.

Agricultural Research Service, U.S. Department of Agriculture

“Cows are natural processors,” Weimer says. “They make their living by eating plants, and bacteria carry out their fiber digestion.”

Weimer says that the bacteria in a cow’s stomach produce many different enzymes that break down the cellulose in grass and other plants in a cow’s diet.

These bacteria hold cellulose-digesting enzymes on their cell surfaces in a structure called a cellulosome. What’s more, the bacteria attach themselves to cellulose fibers in the cow’s stomach and digest them on the spot.

“The bacteria basically glue themselves to the fiber and begin digesting it,” Weimer says. “It works like a disassembly line that takes apart the cell wall.”

Right now, making ethanol from cellulose is expensive. Enzymes are costly to make, and current methods for breaking down cellulose require a lot of energy.

“If we could re-create the activity of the cellulosome,” Weimer says, “we could greatly increase the efficiency and improve the economics of digesting cellulose.”

Increasing production

Another common wood digester is a fungus called Trichoderma reesei. By producing cellulose-digesting enzymes, this fungus breaks down logs in the forest and causes “jungle rot,” which ruins tents and other fabrics in the tropics.

This racing vehicle runs on ethanol.

National Renewable Energy Laboratory

At least one company has developed strains of this fungus that can churn out huge quantities of enzymes.

Advances in ethanol production can’t come soon enough. Last year, President Bush signed a law requiring 7.5 billion gallons of biofuels such as ethanol to be blended with gasoline by 2012. That’s almost twice the amount of ethanol that we produce from corn today.

Maybe, by the time you get your driver’s license, you’ll be fueling up at the ethanol pump.

Going Deeper:

Word Find: Ethanol

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The power of the wind can send a kite into the sky—or supply electricity to homes.

Wind is also an increasingly valuable source of energy—helping to bring electricity into our lives. Without electricity, there’d be no TV, no video games, and no cell phones. We’d have to sit around fires for warmth and eat dinner by candlelight.

At the National Wind Technology Center (NWTC) in Golden, Colorado, scientists are working to improve wind-power technology and lower the cost of generating electricity. The center is part of the National Renewable Energy Laboratory, where researchers look for Earth-friendly ways to power our lives.

A renewable natural resource is one that can’t be used up or one that can be replaced naturally. Sunlight is an example of a renewable resource that’s always available somewhere, and wood is an example of one that can be replaced by new growth. Wind is also a renewable resource.

Wind is the fastest growing source of electricity in the world. It’s often one of the least expensive forms of renewable power available. And it can sometimes be the cheapest form of any kind of power, some experts say.

A modern windmill, like this one in a field in Pennsylvania, has three, streamlined blades for catching the wind and generating electricity.

Roger Czerneda

Generating power from the wind leaves no dangerous waste products behind, says NWTC’s Jim Johnson. Best of all, its supply is unlimited.

“It sounds almost trite to say, but it’s true,” Johnson says. “The wind is always blowing somewhere.”

Catching the breeze

The idea behind wind power is simple. Like pinwheels, windmills are designed to catch breezes, which cause their blades to spin. This motion represents energy, which can then be used or converted into other forms of energy.

People have been harnessing the power of wind for a long time. Some of the first windmills were built more than 5,000 years ago, Johnson says, starting in the Middle East. Back then, people used wind to turn blades that rotated grinding stones that crushed grain into flour.

In the Netherlands, wind power has long been used to pump water. In the United States, a lot of windmills for pumping water, milling grain, and other purposes were built between 1870 and 1930. You can still see them on farms in some parts of the country.

Fifty or more years ago, farmers used windmills like the one shown in the foreground to pump water. Nowadays, farms might have rows of wind turbines generating electricity, which is sold to power grids.

Warren Gretz, National Renewable Energy Laboratory

Old windmills were usually made of wood and had any number of blades. Modern windmills, also called wind turbines, come in a variety of styles and sizes. They’re usually tall, skinny, and made of aluminum or steel. Most have two or three blades that spin on an axle, which is attached to a gearbox.

Nowadays, the blade motion is often converted into electrical energy.

“Think of a small, oscillating fan that you might put on your dresser or desk to make a breeze,” Johnson says. A windmill does the same thing that a fan does—but in reverse. “Instead of consuming energy to power the motor and turn the fan blades, the breeze turns the fan blades, which run a generator that produces electricity,” he says.

The average turbine has blades that carve out a circle about 150 feet wide, Johnson says. The biggest ones have blades that sweep out a circle stretching some 400 feet across. That’s a full football field and a half!

Modern windmills, also called wind turbines, are usually tall, skinny, and made out of aluminum or steel. Most have two or three blades that spin on an axle, which is attached to a gearbox.

A turbine’s height depends on its location. Its blades have to catch gusts at the height above the ground at which the wind tends to be strongest. Some turbines are more than 100 feet tall.

But there’s more to generating electricity than just catching the wind. For one thing, the electricity generated by a windmill has to be converted to different voltages and frequency levels before it can flow through power lines. And, because storing this energy would be inefficient, electricity generated by wind goes directly into the power grid, where it mixes with electrical energy from other sources.

Potential power

The potential for wind power is huge, advocates say.

Right now, the United States gets less than one-tenth of a percent of its electricity from wind energy, Johnson says. Some experts say it’s possible to boost that number to 20 percent—or more.

A wind farm in Pennsylvania.

Roger Czerneda

In theory, North Dakota alone could supply one third of the country’s energy if there were an efficient way to transport the energy to where it’s needed, say experts at the American Wind Energy Association.

The U.S. Department of Energy estimates that the world’s winds could generate 15 times the amount of energy now used around the globe, if only we could tap into them.

Even so, wind energy has its critics, who argue that the system is far from perfect. One of the biggest problems with wind, they say, is its unreliability. Though the wind might always be blowing somewhere at any given time, there’s no guarantee that it would blow all the time at any given place.

The faster and more often the wind blows, the cheaper and easier it is to extract power from it, so wind farms tend to pop up in the windiest places. In the United States, that means states in the Midwest, such as Minnesota and Kansas. California also has large wind farms.

Unfortunately, these places tend to be far from the biggest concentrations of people, who live mostly in cities on the coasts. There’s still no good way to transport wind energy over long distances.

Ugly turbines

Another criticism of wind turbines is more personal. Wind farms take up a lot of space, and some people think they’re just plain ugly.

One of the most controversial projects right now has been proposed for Nantucket Sound, off the coast of Cape Cod in Massachusetts (see www.capewind.org/). Offshore wind farms can be highly productive because the breezes out on the ocean are consistently fierce, but the United States has yet to get one built.

People who oppose wind farms argue that turbines can be noisy, spoil the scenery, harm birds, bats, and other animals, and might even change the local climate.

PhotoDisc

However, some people, including Massachusetts Governor Mitt Romney, are worried that an offshore wind farm would ruin the natural beauty of the area.

Johnson disagrees. “Ugly is in the eye of the beholder,” he says. “It’s ugly if you’re a ‘Not in My Backyard’ kind of person.” People who support renewable energy, on the other hand, often think wind turbines are beautiful.

Other people have complained that wind turbines can be noisy, could affect bird migration, and cause the deaths of bats and other animals. One recent report suggested that large wind farms could even affect an area’s local climate.

Paul White owns a wind-power development company in Minneapolis called Project Resources Corporation. He sees great value in the wind-energy business.

“My whole life has been powered by wind power for over 10 years,” White says. “Everything I purchase, drive, sleep on, read, and eat was paid for by the proceeds from selling electricity generated by the wind. Everything.”

“I’ll be living off of wind power the rest of my life, as will all of my employees and their families, assuming the wind keeps blowing, which I’m willing to bet on,” he adds.

There’s still a lot of research to be done on making sure that wind power does it job efficiently, safely, and cheaply. That’s where the engineers and other researchers at NWTC and elsewhere come in.

And that’s where you can make a contribution if you do a science project involving wind energy and turbines (see www.kidwind.org/materials/sciencefairideas.html).

Wind power has the potential to ease the world’s dependence on fossil fuels and to help clean up the environment. It’s worth the effort.

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You might want to dwell a little longer on the conditioned air that magically wafts out of household vents, however. The way you heat or cool your home has a big effect on the Earth, says John Carmody. He’s director of the Center for Sustainable Building Research at the University of Minnesota in Minneapolis.

“Most people don’t usually think about where their heat comes from,” Carmody says. Yet nearly every type of energy source dumps waste or spews pollution into the air.

Heating and cooling the millions of buildings in the United States require a lot of energy and have a huge impact on the environment.

South Florida Restoration Science Forum, U.S. Geological Survey

Buildings have a huge impact on the environment. There are more than 81 million buildings in the United States, according to the U.S. Department of Energy. Buildings consume more energy than any other economic category, including transportation and industry. Almost half of the energy that buildings use goes into heating and cooling.

Like Carmody, a growing number of engineers, planners, and architects have been looking for new ways to make buildings less wasteful and kinder to the environment. Improvements have come in many forms, including better insulation, windows, and construction materials.

Architects are also realizing that the size, location, and positioning of a building affects how much energy it uses. Even the arrangement of buildings in a neighborhood makes a difference.

“In the last 10 years,” Carmody says, “there has been a major movement toward what you’d call ‘green’ buildings.” Such buildings are sometimes also described as sustainable, environmentally friendly, or healthy.

Temperature control

The amount of energy you use for heating and cooling depends on where you live.

In places such as San Diego, Calif., for instance, the temperature is mild all year round. People rarely have to regulate the temperature of their homes.

Where I live in Minnesota, on the other hand, winters are unbearably cold, and summers can be unbearably hot. Without heaters and air conditioners, we’d be in big trouble. (At least, I know I would be pretty miserable.)

Transmission lines carry electricity from power plants to communities.

Oak Ridge National Laboratory

To get a sense of your own environmental impact, you can look at the climate where you live. Ask yourself how often you turn on the heater or the air conditioner, and how high you pump them up.

You might also want to figure out the source of the energy that your house or school uses for temperature control. Most air conditioners run on electricity. Some heaters do, too. If you find a furnace in the basement and radiators around your house, though, that probably means you have a system that burns natural gas or oil to heat water.

These energy sources have their downsides. Electricity, for example, usually comes from power plants that burn coal or use nuclear fuel. Both produce dangerous waste.

And there’s energy lost along the way. “Only about a third of the energy generated at a power plant makes its way to a house,” Carmody says.

One alternative energy source is to use wind to generate electricity.

U.S. Department of Energy

As an alternative energy source, harnessing the power of the wind or sun is becoming more popular in some places. Windmills for generating electricity are springing up from California to Germany. And researchers are working to make solar cells, which absorb light from the sun and convert it into electricity, more efficient.

Sunlight can also be used to heat tanks of water. Still, the technology needs some work. For now, solar power is more expensive than traditional sources. And some places don’t have enough reliable sunshine or wind to make these approaches practical.

Windows, walls, and roofs

No matter where the energy comes from to heat or cool your home, simple design and construction choices can have a big effect on how much energy you end up using.

First, consider when your home was built. Old houses tend to be drafty, Carmody says. They lose energy to the outdoors.

Newer buildings have more insulation packed into the walls. Fluffy materials such as fiberglass and Styrofoam have lots of pockets for trapping air. Such a structure holds heat in, just like a cozy sleeping bag. Many environmentalists prefer cellulose fiber, which is made from recycled paper and wood, for insulation.

When it comes to energy efficiency, windows are a big issue. Instead of just looking through them, take a closer look at the windows where you live. If you can feel cold air rushing in even when the window is closed, that’s a good sign that you’re wasting a lot of energy.

Researchers can monitor the energy efficiency of a wall and window combination.

Oak Ridge National Laboratory

New technologies are drastically improving window performance.

Windows used to be made from single sheets of glass. Today, windows are almost always double-glazed. This means there are two panes of glass set in a frame with an air space between them for insulation. Sometimes, windows are triple-glazed.

Scientists have also developed special coatings for windows. These invisible materials reflect heat. In a double-glazed window, coating the two sides of glass that face each other traps heat between the panes and increases insulation.

Chemists in England recently developed a kind of “smart” window coating. It reflects heat, but only when the window gets warmer than room temperature. If the technology becomes more affordable and practical, it could make windows even better at keeping the inside air in and the outside air out.

On the other side of the temperature fence, researchers from Oak Ridge and Lawrence Berkeley National Laboratories are working on a new type of roofing material that they hope will cut the cost of air conditioning by 20 percent.

At Oak Ridge National Laboratory, researchers test “cool-color” roofing materials, which reflect more sunlight than typical shingles or tiles do.

Oak Ridge National Laboratory

If you’ve ever worn a black T-shirt on a sunny day, you know that dark colors absorb light and create heat. Most roofs are dark, so they absorb infrared and visible light, which makes a building warmer. The idea is to make shingles with colors that reflect certain wavelengths of sunlight. Such “cool” roofs should be available in 3 to 5 years, the scientists say.

Living spaces

Perhaps the most innovative strategy for increasing energy efficiency actually has nothing to do with technology. Instead, architects take advantage of the environment and landscape to control temperature inside a building.

In the northern hemisphere, this can mean installing lots of south-facing windows so that plenty of sunlight can pour in. At the same time, well-designed overhangs keep summer sun out but let winter sun in.

Some people are choosing to live in communities that have been specifically designed to promote energy-efficient living. Village Homes in Davis, Calif., was one of the first of such green, or sustainable, developments.

Completed in 1981, the neighborhood has a network of paths that encourages people to bike or walk instead of drive (and pollute). The development’s 240 houses face south for lots of exposure to the sun. Overhangs provide shade. Houses run on solar power. There are lots of trees. And narrow streets have as little pavement as possible.

The strategy seems to be working. The air temperature around Village Homes is 15 degrees F. cooler than surrounding areas that have more pavement. And residents spend between one-third and one-half as much on energy bills compared to more conventional homes in nearby neighborhoods.

“We have a shadier, cooler microclimate,” says developer and resident Judith Corbett, who spoke at an environmental design conference in Minneapolis last April. “I don’t even have an air conditioner.”

As people see communities such as Village Homes thrive, these types of developments are becoming more popular. They’re springing up in places such as Colorado, Arizona, Virginia, and Australia.

Zero energy

The U.S. government itself is taking steps to boost the energy efficiency of the nation’s buildings. In one project, the Department of Energy has a long-term goal to create a “net-zero-energy” house—a house that wastes no energy.

In Tennessee, builders are putting up a house that should produce about as much energy as it uses. The roof and walls are made from special insulated panels, and solar cells on the roof generate electricity for the home.

Oak Ridge National Laboratory

The Department of Energy’s development of “near-zero-energy” homes is one step in that direction. One such house in Tennessee runs completely on electricity for just 82 cents a day. Conventional homes in the same area use between $4 and $5 in electricity a day.

As research on efficient energy use continues, think about what you can do to live a more energy-efficient life in the meantime.

Keep the heat low or off when you’re not home. Make sure leaks around doors and windows get patched. Turn off lights, TVs, and computers when they’re not needed.

Better yet, if you’re cold, put on a sweater and have a hot drink. If you’re hot, consider having an ice cream cone or going for a swim.

Going Deeper:

Word Find: Hot and Cold

Additional Information

Questions about the Article

Energy Facts

Energy use in the United States (Quadrillion Btu)

Btu, short for British Thermal Unit, is a unit of heat energy. One Btu is the amount of heat needed to raise the temperature of one pound of water 1° F. The heat given off by burning one wooden kitchen match is about 1 Btu.

Source: Energy Information Administration, U.S. Department of Energy

Now, environmental engineers from Pennsylvania State University have found a use for all that waste material—as an energy source. Using a type of energy generator called a fuel cell, they can break down plant and animal, or organic, waste and, in the process, produce electricity. Their technique could reduce the cost of treating water.

As wastewater flows through this new type of fuel cell, microbes break down organic matter and release electrons, which flow from the negative electrodes (green) to the central positive electrode (red).

T. Schindler/National Science Foundation

Once you flush the toilet, you probably forget about whatever you just dumped in there. Every year, though, the United States alone spends $25 billion to clean up sewage. Many countries can’t even afford to treat their water.

The new fuel cell is a small plastic cylinder. Inside, eight rods made of graphite (the black stuff that’s in a pencil) act as negative electrodes. The rods surround a hollow tube made of carbon and platinum, which acts as a positive electrode.

When wastewater is pumped through the fuel cell, bacteria already present in the water stick to the graphite rods. As the microbes break down the organic matter in the water, they generate electricity.

Current water treatment techniques are expensive because they use bacteria that need a steady supply of oxygen. The new process could be more efficient, equally effective, and much cheaper, the researchers say. With improvements, such a fuel cell could provide enough power to pump an entire community’s sewage.

Talk about powerful poop!—E. Sohn

Going Deeper:

Goho, Alexandra. 2004. Special treatment: Fuel cell draws energy from waste. Science News 165(March 13):165. Available at http://www.sciencenews.org/articles/20040313/fob5.asp .

Sohn, Emily. 2003. Eating up foul sewage smells. Science News for Kids (May 14). Available at http://www.sciencenewsforkids.org/articles/20030514/Note3.asp .

You can find out more about how a sewage treatment plant works at www.oberlin.edu/envs/ajlc/Systems/Water/Wastewater/SewageTreatment.htm (Oberlin College).

Learn more about fuel cells at www.eere.energy.gov/hydrogenandfuelcells/fuelcells/ (U.S. Department of Energy).